The invention relates to a turbine wheel for a turbine of an exhaust gas turbocharger.
Turbine wheels of this type for exhaust gas turbochargers are already sufficiently well-known generally from the prior art and specifically from series vehicle construction. Such a turbocharger is used, for example, in an internal combustion engine of a motor vehicle in order to provide the corresponding internal combustion engine with compressed air. In the finished manufactured condition of the respective turbine, the relevant turbine wheel is arranged in a corresponding turbine housing of the turbine, and in this configuration exhaust gas can thus flow against it and drive it. For this purpose, the turbine wheel comprises at least one turbine blade against which exhaust gas can flow. The turbine generally includes a plurality of turbine blades arranged sequentially in a circumferential direction with respect to the turbine wheel that are connected to a common hub and are thus formed as one piece with the hub.
It is known to produce the respective turbine wheel by casting, meaning by using a casting process. It has proven advantageous to manufacture the turbine wheel using a precision casting method. However, turbine wheels generally have thick turbine blades on their corresponding wheel outlet. In other words, the turbine blades of conventional turbine wheels are typically thick at the wheel outlet in order to be able to manufacture the turbine wheels by casting. Thick turbine blades, however, cause high flow losses and thus lead to a deterioration of efficiency, whereby the efficiency of the turbine as a whole is impaired.
It is therefore the object of the present invention to further develop a turbine wheel of the aforementioned type so that the turbine wheel may be manufactured by casting, specifically by precision casting, wherein an especially high degree of efficiency of the turbine can be realized using the turbine wheel.
In order to further develop a turbine wheel in such a way that the turbine wheel may be manufactured by casting, specifically by precision casting, wherein an especially high degree of efficiency of the turbine can be realized via the turbine wheel, it is provided according to the invention that a maximum ratio of the wheel outlet diameter of the turbine wheel to the thickness of the turbine blade is 111.75. The thickness of the turbine blade is referred to as the blade thickness, the wheel outlet diameter being a diameter on which or over which exhaust gas flows through the turbine wheel during operation of the turbine.
In addition, it has proven especially advantageous if the turbine blade has a maximum taper angle of 8 degrees. This means that the turbine blade is preferably angled in a radial direction from the outside inward of no more than 8 degrees. Surprisingly, it has been found that by maintaining the specified ratio, particularly in connection with maintaining the taper angle, a particularly advantageous production of the turbine wheel may be realized, specifically by casting, because, in using this ratio, in particular in connection with the taper angle, an across-the-board thickening of the turbine blade may be avoided. It is thus possible to create a geometrical optimization between thermodynamics, operational life and casting-process production so that the turbine wheel may be manufactured economically and with an especially high quality, specifically casting quality. This leads to an increase in operational life compared to conventional turbine wheels. In addition, the turbine wheel according to the invention may be produced using small amounts of materials and thus in a manner that minimizes weight and expense.
Additional advantages, features and details of the invention are shown in the following description of a preferred exemplary embodiment as well as in reference to the drawings. The features and feature combinations mentioned above in the description, as well as the features and feature combinations mentioned below in the description of the Figures and/or shown in the Figures alone may not only be used in the particular specified combinations, but also in other combinations or singly, without departing from the scope of the invention.